Hi,
Sorry this is long, trying not to drip feed...
DD2 has never managed to sleep for more than 4 hours at a time. (I can probably count on one hand). Usually it's 1.5-2 hour stretches. She is now a year old and I'm losing the plot!
Bit of background-had a huge amount of stress during my pregnancy. When she was born, she needed to be held all the time (and I do mean ALL the time), and mostly by me. She would get upset very quickly if DH tried to settle her, and only once in a blue moon was my mum able to help. She was also a very sucky baby, and would cry after feeds unless we gave her a finger to suck. (No evidence of colic/reflux etc). Slept on her tummy on my chest, with her head right up under my chin. We gave in and gave her a dummy, which helped her to settle a bit, but mostly because with DD1 around, I couldn't just sit all day with my finger in her gob!
I assumed this was mostly due to stressful pregnancy, and would settle if we met her need for security and comfort.
Fast forward to now, age 1 year, we've created a monster and I'm on my knees. She will only fall asleep in my (or DH's) arms, (doesn't tend to fall asleep on the boob) and wakes frequently through the night for BF. She is sleeping in until aprox 6am now, which is an improvement on 5! Naps in the day are usually only 45 minutes long, in which case she may manage 2, or if she naps a bit later may manage 1.5 hours, but not always. She does look tired, so I don't think this is enough.
In general, she is a heavenly ray of sunshine! She plays happily, amuses herself in a way DD1 never did, smiles all day and is generally wonderful to be around. And then it's bedtime again.
We recently started trying to sleep train, starting with trying to get her to go to sleep in her cot. (CIO and CC not for us). Solid bedtime routine, at the same time each day (as it's been since she was 3 months old). Put her down and she starts playing. Removed everything of interest from her cot. We lie down next to her, but no eye contact and no interaction, except to occasionally sshhh her if she starts cranking up. If we try to gently lie her down she thinks it's a game and gets up faster, so at the point of slam dunking her in frustration we've stopped doing that 
The first night, it took an hour. Tonight is the 12th night, it still takes an hour!
I know gradual withdrawal takes longer than the extinction methods, but should we not have seen some improvement yet? Or do we just have to stick with it?
Any advice/experience gratefully received.